A linear guide apparatus is an apparatus which includes a guide rail, a slider, and multiple number of rolling elements, the guide rail and slider have rolling surfaces, respectively, which are disposed so as to face with each other to form a rolling channel for the rolling elements, and the rolling elements roll over such a rolling channel so that either one of the guide rail or the slider takes a linear motion with respect to the other.
According to conventional linear guide apparatuses, side seals each having a rubber lip which contacts the guide rail in a sliding manner are disposed at both ends in the direction in which the slider moves. This prevents foreign materials from entering into the interior from both ends of the direction in which the slider moves linearly.
Conventionally, there is proposed to employ an integral double-lip structure to the lip of the side seal, thereby improving both dust proofing performance and sliding performance (see, for example, Patent Document 1). Patent Document 1 also discloses that the double-lip structure is formed by an external lip directed to the exterior and an internal lip directed to the interior. The external lip accomplishes the sealing performance (the dust-proof performance) against the dusts, etc., outside the slider and the internal lip accomplishes the sealing performance (hermetical sealing performance) against greases, etc., inside the slider.
However, the integral double-lip structure has a difficulty to surely attach both lips to the guide rail in a tight-contact manner. Even if the integral double-lip structure can be surely attached, a tip of another lip is pushed and lifted by the one lip when the slider moves, and foreign materials may be trapped in a space formed between the lifted tip and the guide rail.
Moreover, when the linear guide apparatus is used in especially dusty environments, side seals are doubly attached in an overlapped manner to improve the hermetical sealing performance and the repelling performance of sticking foreign materials (see, for example, Patent Document 2, paragraph) Patent Document 2 also discloses that an interspace member is disposed between the two side seals, and those side seals and the interspace member are fixed together to the end face of the slider by an attaching bolt. However, it is difficult to simultaneously attach the two side seals highly precisely.